1. Field of the Invention
The present invention relates to a modular ship complex equipped so as to perform operations in a marine environment, such as, for example, laying submerged conduits. The invention relates in particular also to modules that are usable in the ship complex.
2. State of the Prior Art
In the prior art, vessels are known that are equipped with apparatuses that are suitable for laying submerged conduits, such as, for example, pipelines or the like.
The conduit can be of different types and sizes according to the technical specifications that it has to meet, and it can be installed in very deep, deep or medium to shallow waters.
Depending on the cases, various equipment has to be used that is suitable for laying the conduit according to particular laying modes.
For example, the ship can be set up with equipment for the so-called “J-lay” mode, i.e. with the partially submerged conduit positioned on the sea bed according to a J-profile that is almost vertical at the vessel.
The equipment comprises a supporting tower that is suitable for supporting an additional, almost vertical, pipe portion that is welded each time to the end of the partially submerged conduit so as to extend the conduit.
The vessel is provided with tensioning means for tensioning the conduit during the laying down step.
The pipe trunks to be joined to form the conduit are loaded onto the vessel from barges or supply vessels during the operative step, for example by cranes.
Alternatively, the vessel could comprise equipment suitable for laying in “S-lay” mode, i.e. with the partially submerged conduit arranged according to an S-profile whilst the conduit positions itself on the sea bed during laying.
At the stern of the ship there is arranged a structure with an arched profile (called a “stinger” in the relevant jargon) to support the conduit portion that is leaving the ship. The vessel is provided with joining stations that gradually extend the conduit by joining additional trunks of pipe and the free end thereof.
The conduit is maintained taut during laying by means of suitable tensioning apparatuses.
According to other techniques, on the vessel there are installed pipe reels made of stiff steel or reels of flexible pipe that supply portions of conduit during laying. The pipe intended to be laid can be wound on the suitable housings whilst the ship is stationary in port, with an operation that usually requires a certain lapse of time. Also in this case, the equipment intended to extend the pipe comprises suitable tensioning means for tensioning the conduit.
The vessels in question involve a very high investment cost, owing to the considerable size of the vessels and the sophisticated technology used therein (think, for example, of the propellers, the installed power, the dynamic positioning system, or still other things). Therefore, there is very great interest in making the vessel work in the most continuous and productive manner.
Nevertheless, whatever the type of laying equipment integrated in the vessel, the pipe-loading step (in a reel or trunks) requires a considerable outlay of time, which greatly affects productivity, requiring considerable periods stationary in port, to prepare the equipment for the subsequent work.
Further, each vessel has integrated into the structure a different type of equipment for laying the pipe, for example equipment for “J-lay” mode, “S-lay” mode or for laying from pipe reels (also known as “carousels”).
For the various types of laying required, a different suitably equipped vessel is necessary. In order to meet in a flexible manner the various needs that may arise in the various practical applications, several variously equipped vessels must be available. Obviously, this situation entails very high investment costs.
The general object of the present invention is to remedy the aforesaid drawbacks by providing a modular ship complex that enables various types of submerged conduit to be laid.
A further object of the invention is to provide a modular ship complex that enables great operating efficiency and flexibility.
A further object of the invention is to provide equipped modules that are suitable for being used in the aforesaid modular ship complex that enable great flexibility to be obtained in the type of submerged pipe laid and enable the efficiency of use of the laying equipment to be increased.